What It Means
A water heater flush drains the tank and runs fresh water through it until the sediment that collects at the bottom washes out. Minerals in the water, especially hard water, leave calcium and magnesium deposits that make a heater work harder and less efficiently. Tankless units get the same treatment in a different form, usually called descalingDescalingDissolving the mineral scale that hard water leaves inside kettles, coffee makers and other appliances that heat water. See more, because the deposits build up inside the heat exchanger.
Try It: How Often Does Your Water Heater Need Flushing?
Pick your heater and your water, and see the makers' usual schedule. Your own manual has the final word.
About once a year
About every 6 months
Bradford White recommends a professional descaling every 6 to 12 months for tankless units.
Power off, water off and a cool tank come first. Hot water scalds.
How It Sounds at Home
- "Is it time to drain the water heater again?"
- "I flushed the tank on Saturday and it was full of grit."
- "I put the water heater flush on the calendar."
The Breakdown
How often, per water heater makers (Rheem, A. O. Smith, Bradford White)
| Heater and water | How often |
|---|---|
| Tank, typical water | About once a year |
| Tank, hard water | About every 6 months |
| Tankless, typical water | About once a year |
| Tankless, hard water | About every 6 months, with Bradford White advising professional descaling every 6 to 12 months |
The makers' steps for a tank flush
- Turn off the electricity or gas and the cold water supplyMilk supplyHow much breast milk a parent's body makes. It's driven by supply and demand: the more often milk is removed, the more the body makes. See more to the heater. A. O. Smith suggests leaving it off a few hours first so the water can cool.
- Connect a garden hose to the drain valve and run it somewhere hot water can't do damage.
- Open the pressure relief valve, then the drain valve, and let the tank empty.
- Flush with cold water until the water from the drain runs clear of sediment.
- Close the drain valve, take off the hose and close the relief valve.
- Open the hot water faucets in the house and turn the cold supply back on. Once water flows from each faucet, turn them off, and only then restore the power or gas.
Keeping it good between flushes. Mineral depositsHard water stainsWhite, chalky marks left on glass, faucets, tile and toilets when hard water dries and leaves its calcium and magnesium behind. See more are what the makers say cut a heater's efficiency, so hard water is the main reason to flush more often. Put the date on the calendar, and check your model's manual for anything specific to it, including its own interval.
Good to Know
This job involves scalding water, gas or electric power and a tank under pressure. Follow your heater's manual, since the makers say to defer to your own model's handbook, and call a licensed plumber if you're unsure about any step, the drain valve won't open or close properly, or the heater is gas and you aren't comfortable relighting it. Buhata's own safety rule: if you smell gas, leave the house and call your gas company, or 911 in an emergency, from outside.
FAQ
How often should you flush a water heater?
About once a year for most homes, and about every 6 months with hard water, according to Rheem and A. O. Smith. Your manual may give a different interval for your model.
Do tankless water heaters need flushing?
Yes. Makers recommend flushing or descaling about once a year, more often with hard water, because minerals build up in the heat exchanger. Bradford White advises a professional descaling every 6 to 12 months.
Why do you turn the power back on last?
The makers' steps put it last. Refill the tank and wait until water flows from each hot faucet, then restore the electricity or gas, in that order.
Do It in Buhata
Maintenance
Add "Flush the water heater" to Maintenance in your Household X add-on on a yearly schedule (every 6 months with hard water), so it rolls forward each time you tick it.
Open BuhataRelated Terms and Categories
- Anode rod
A metal rod inside a tank water heater that corrodes on purpose, so the steel tank doesn't. Makers suggest checking it yearly or every few years.
- Tankless water heater
A water heater with no storage tank that heats water as it flows through, only when a hot tap is on. Also called a demand-type or instantaneous water heater.
- Water softener
A home system that removes the calcium and magnesium that make water hard, usually by trading them for sodium in a tank of resin beads.
- Descaling
Dissolving the mineral scale that hard water leaves inside kettles, coffee makers and other appliances that heat water.
- Appliance lifespan
How many years a home appliance usually lasts before it needs replacing, from about 6 years for a compactor to 15 for a gas range in Consumer Reports' 2009 figures.
Sources
Rheem, "How Often To Flush Your Water Heater (And How To Do It)"; Rheem, "How to Keep Your Tank and Tankless Water Heaters Running at Peak Performance"; A. O. Smith, "How to Drain & Flush A Water Heater"; A. O. Smith, "Water Heater Maintenance Checklist"; Bradford White, "Why Your Tankless Water Heater Needs Professional Descaling and Flushing"
- www.rheem.com/water-heating/articles/how-often-to-flush-your-water-heater-and-how-to-do-it
- www.rheem.com/water-heating/articles/how-to-keep-your-tank-and-tankless-water-heaters-running-at-peak-performance
- www.hotwater.com/info-center/how-to-drain-a-water-heater.html
- www.hotwater.com/info-center/water-heater-maintenance-checklist.html
- www.bradfordwhite.com/blogs/why-your-tankless-water-heater-needs-professional-descaling-and-flushing
Last updated .